Dual oil burner with common air and oil control



I March 15, 1949. J. A. LOGAN ETAL 2,464,697 DUAL OIL BURNER WITH COMMON AIR AND OIL CONTROL Filed Feb. 13, 1948 5 Sheets-Sheet 1 INVENTORS JoazrnA. loc /m BY A/mPmuP/Y. B/LLJ 4 zz e ATTORNEYS March 15, 1949. J. A. LOGAN ETAL' 2,4649697 DUAL on, BURNER wz'ra COMMON AIR m OIL CONTROL 5 Sheets-Sheet 2 Filed Feb. 13, 1948 INVENTORS har /1 A L OGA/Y AflnP/m/PH 31. .1.6

ATTORNEYS Mar h 15,1949. J. AQLQGAN m. 2,464 6 DUAL OIL BURNER WITH COMMON AIR AND OIL CONTROL Filed Feb. 13, 1948 5 Sheets-Sheet 4 INVENTORS Juan! A. .loqmv BYA/YD PIlILlPfl.B/LLJ March 15, 1949. J. A. LOGAN ET AL 2,4645%? DUAL OIL BURNER- WITH common AIR AND OIL CONTROL Filed Feb. 15, 1948 5 Sheets-Sheet 5- INVENTORS Joszm A. Low/y BYAND PHIL/P ACE/1.1.6

- 9 ATTOR EYS Patented Mar-.15, 1949 DUAL OIL BURNER WITH COMMON AIR AND OIL CONTROL Joseph A. Logan, Hadley, and Philip H. Bills, Longmeadow, Mass., assignors to Gilbert & Barker Manufacturing Company, West Springfield, Mass., a corporation of Massachusetts Application February 13, 1948, Serial No. 8,184

Various examples of dual burners for the purpose described will be found in the prior art. In some cases, the two burners may be operated alternately or simultaneously while in others alternate operation of the two burners is compelled but in no case, so far as we are aware, can both burners be operated with the same and high efliciency. According to this invention, the two burners must operate alternately.

The object of this invention is to provide in a burner of the type described, improvements, which will-enable each heating appliance to be fired with the same and high efliciency so that each burner will work as well as the other.

For the above purpose, it is important that the rates at which air is supplied by the one fan to the two burners be adjustable accurately, the one be supplied to each burner at precisely the right rate with respect to the rate of oil flow from such burner to produce the desired high degree of combustion eiiiciency. With each burner thus arranged to be set for operation at high combustion efiiciency, the supply of air and oil may be automatically shifted from one burner to the other for individual operation of the burners so that each may'function at the high efliciency, for which it is set, without affecting the other since joint operation of the burners is precluded.

The invention will best be understood from the detailed description of the one example shown in the accompanying drawings, in which:

Figs. 1 and 2 are exterior side elevational and top plan views, respectively, of adual. oil burner embodying the invention;

Fig.- 3 is a sectional plan view, taken on the line- 33 of Fig. 1 and drawn to a larger scale, showing the air valve for connecting one or the other of the air conduits to the outlet of the fan casing;

Fig. 4 is a sectional elevational view of the burner, taken on the line 44 of Fig. 2';

Figs. 5 and 6 are sectional plan views taken on the lines 5- 5 and 6-6, respectively, of Fig. 4;

Fig; 7 is an end elevational view, partly in section to show the air shutter and mechanism for moving it from. one position to another to secure different rates of air flow and the precision ad- 5 Claims. (Cl. 158-28) 2 justing means for accurately determining said positions;

Fig. 8 is a diagrammatical-view of the system for supplying oil to the atomizing nozzles and the hydraulic motors used to operate the air shutter'and air valve; and

Fig. 9 is a diagrammatical view showing an electrical system for controlling the burner.

tion zones.

Referring to these drawings: Figs. 1 and 2 show the general arrangement of parts of the dual burner of this invention. This burner includes a single power-operated unit for supplying air and oil for combustion to either of the two burners and thus to either of two combus- This unit is best shown in Fig. 7 and comprises an air supply'fan I and an oil supply pump 2, both driven by an electric motor 3. As shown, the hub of the fan is fixed directly to the shaft 4 of the motor. The shaft 5 of pump 2 is fixed to the drivenelement 6 of a centrifugal clutch, the driving element I of which is connected by a flexible coupling 8 to the hub of fan I. The clutch arrangement may be that of Logan Patent No. 1,985,934, granted January ..l, 1935, and is arranged to connect the pump 2 to the motor 3 only after the latter and the fan I have attained a predetermined high speed and to disconnect the pump from. the motor,

arms I4 (Fig. 2), the outer ends of which are integrally connected by a cross bar I5, in which the oil pump 2 is suitably supported, as indicated in Fig. 7. In the lower part of the casting I 2 is a cylindrical opening I 6 (Fig. 4) into which the fan discharges through its outlet II. This passage is closed at one end by a cover I'I, suitably secured as indicated, to the casting I2. The opposite end of passage I8 communicates with, a chamber. I8 (Fig. 3), formed within a sheet metal casing I9 of square cross section and secured as indicated to the casting I2. Connected to this casing I9 are two air conduits 20 and 2| which extend to two different combustion zones. As shown in Fig. 1, the conduit 20 leads .to, and has its open outlet end communicatin with, the combustion chamber 22 of a warm air furnace, shown in part at 23 and adapted for house heating, and the conduit 2| leads to, and has its outlet end communicating with, a chamber 24 in a hot water heater, shown in part at 25 and adapted to heat a supply of hot water for household use. A pedestal 25' is provided to support the conduit 2|.

The one fan I may be connected to supply air to either air conduit 20 or 2| by means of an air valve 26 (Fig. 3). A partition 21 extends diagonally across the chamber l8 and has an opening 28 therein. The air valve is suitably fixed to a shaft 29, rotatably mounted near its ends (Fig. 4) in the upper and lower walls of easing IS. The air valve Is movable from the position shown in Fig. 3 in which it closes the outlet 39 to air conduit 2| and opens the outlet 28 to conduit 20, to a position, in which it closes the outlet 28 and opens the outlet 39. Thus, either one of the air conduits may be connected to receive air from fan This air valve is automatically moved from one of the described positions to the other by means of a hydraulic motor. This motor includes a cylinder 3| (Fig. 2), fixed to the upper wall of casing 9, a piston 32 reciprocable in the cylinder, a piston rod 33 and a spring 34, located in the cylinder and encircling the rod 33 and adapted to hold the piston at one end of the cylinder. The outer end of rod 33 is pivotally connected to a gear segment 35, mounted on a stud 33, fixed to the upper wall of casing |9 and meshing with a pinion 31, fixed on the upper end of the shaft 29 of air valve 29. The spring 34 holds this valve in position to close the outlet 30 and thus prevent flow of air from the fan to the air conduit 2|, which supplies the hot water heater combustion zone, and open the outlet 28 and connect the fan to the conduit 20, leading to the hot air heating combustion zone. When oil is admitted to the cylinder 3|, by means later to be described, the piston 32 will be moved against the force of spring 34 to carry the air valve 25 into position to close the outlet 28 and open the outlet 30, thus allowing fan to supply air to the air conduit 2| which leads to the hot water heating zone.

Located in the air conduits 20 and 2| are oilatomizing nozzles 38 and 39, respectively, each adapted to supply a spray of finely divided oil particles to be mixed with the air supplied, as above described. Suitable ignition means, such asthe pairs of spark electrodes 40 and 4|, supplied with high tension current by means to be later described, are provided one pair in each air conduit to ignite the combustible mixture of air and oil. The nozzles 38 and 39 are supplied with oil under proper pressure through oil conduits 42 and 43, respectively, adapted to be connected, by means to be described, one at a time, to the oil pump 2. These nozzles 38 and 39 will, in the usual case, have diiferent firing rates, suitably proportioned for the heating work to be per- 'formed. The nozzle 39 will generally have the smaller firing rate. Each nozzle is preferably of the so-called mechanical or oil pressure atomizing type.

In many cases, the hot water heater may be adequately fired at a rate considerably less than one gallon an hour, say for example, one halfgallon an hour. A mechanical atomizing nozzle having an orifice small enough to emit oil at such a low rate under efiicient atomizing pressures is easily and frequently clogged. When the perforated nozzle orifice is made large enough to avoid easy clogging, the low rate of oil emission will not be had unless the pressure is greatly reduced, say to one-quarter of the normally efllcient atomizing pressure, with the result that the oil cannot be efflciently atomized and mixed with air by the ordinary methods In such cases, it is preferred to mix the air and oil substantially in the manner disclosed in Logan Patent No. 2,411,048, granted November 12, 1946. A perforated cylinder (Fi 4) formedin two axially aligned sections 44 and 45, is mounted inside the air conduit 2| near its outer end. For convenience in mounting, the conduit 2| has a separate end section 2| and these parts 2| and 2| have annular flanges 46 and 41, respectively. The sections 44 and of the perforated cylinder also have annular flanges 48 and 49, respectively, which abut and are clamped between the flanges 46 and 41 by a series of screws 50. The perforated cylinder is thus supported from the air conduit 2|. The outer end of section 2| is inturned to engage the outer periphery of the section 44 of the cylinder, thus forming annular chambers 5| and 52 around the sections 44 and 15, respectively. Air forced by fan I into conduit 2| enters chamber 52 and thence passes through openings 54 and 53 in flanges 49 and 38, respectively, into chamber 44. Air from these chambers passes through a multitude of closely spaced perforations 55 in the peripheral wall of the cylinder in many radial jets to mix with the oil spray emitted from nozzle 39. The inner end 56 of the section 45 is of frusto conical form, having a central hollow hub 51, in which the nozzle-bearing end of oil conduit 43 is suitably fixed, as indicated. This frutso-conical part 56 is also provided with many perforations 58, through which air from conduit 2| passes in jets to mix with the oil spray from the nozzle 39. This part 56 has two larger openings through which the spark electrodes 4| extend, terminating in igniting relation to the spray from nozzle 39. These electrodes 4| are supported in insulators 59, mounted in a support 60, fixed to oil conduit 43. Preferably, one of the flanges, as 48, of the perforated cylinder is angularly adjustable relative to the other flange 49 so that the holes 53 may be moved from a position of registration with holes 54 to various other positions in which the holes 53 are to varying degrees out of register with holes 54. In this way, the amount of air passing into the chamber 44 may be varied. As shown in Fig, 5, the flange 48 has a series of slots 6| through which the retaining screws 50 pass, thereby enabling the flange and the section 44 to be turned slightly, when screws 50 are loosened, for the purpose described. The flange 48 may have an outwardly projecting lug 62 for convenience in turning this flange.

For the hot air heating zone, the atomizing nozzle 38 is located near the open outlet end of air conduit 20 and produces a conical spray outside the conduit in the combustion chamber 22 of the warm air furnace 23. The air flowing through conduit 20 is directed into the oil spray by a deflector 63 on the end of the conduit and the mixture is ignited by the spark electrodes 40.

It will be understood that the air may be supplied to and mixed with the oil spray from the nozzle 38 in the same manner that it is supplied to and mixed with the spray from nozzle 39.

The latter method may be desirable even though it is not necessary, as it is in the case of a low capacity nozzle, such as the nozzle 39.

Also, if

the nozzle 88 has a sufllciently large capacity, such as one gallon per hour or more, then the air may be supplied to and mixed with the oil spray from the nozzle 39 in the same way that it is supplied to and mixed with the oil spray from the nozzle 38.

The ignition electrodes 40 (Fig. 3) are mounted in insulators 64 fixed as indicated to a support 65, in which the outer and nozzle-bearing end of the oil conduit 42 is also fixed. The support 65 (Fig. 4) is suitably'fi'xed as by the screws 88 to conduit 28. The electrodes 40 are connected by wires 61 (Fig. 3) to the high tension terminals 68 of an ignition transformer which is mounted in a case 69, fixed to one side wall of the casting l2. The assembly of nozzle and electrodes may be removed or replaced through an opening in conduit 20, which opening is normally closed by a cover 10, secured as indicat- 'ed to the conduit. With the cover removed, ac-

cess is had for the connection or disconnection of the wires 61 and for'the connection or disconnection of the oil conduit 42 at the union H.

.The electrodes 4| are supplied with high tension current from a separate transformer mounted in a case '12, fixed. to the conduit 2! (see Figs. 4 and 7). The wire connections have not been shown, except diagrammatically in Fig. 9, but they will be similar to those shown for the electrodes 40. An opening, normally closed by a cover 12', is provided in air conduit 2| to permit access for the connection or disconnection of the wires to or from the electrodes and for connection or disconnection of the oil conduit 43 at the union 13, With these wires and the conduit 43 disconnected, the assembly of nozzle 39, electrodes 4| and perforated cylinder 44, 45 may be removed with conduit section 2i, when the screws 58 are removed.

The oil supply system is shown in its entirety in a single diagrammatical view in Fig. 8. The

various elements of the system, such as the pump, the pressure regulating valves, the firing rate selector valve, and the hydraulic motors, together with the necessary pipe connections, are shown with their mounting and arrangement in relation to the burner, partly in each of Figs. 1, 2, 3, 4 and 7. However, an understanding of the system can be more easily and quickly obtained from the diagrammatical showing of Fig. 8.

The pressure regulating valve for the high rate nozzle 38 is shown as incorporated into the casing of pump 2. A valve 14 is urged by a spring 15 against a valve seat 16 to close off communication between a chamber 11, which is connected by means not shown to the outlet of the pump, and an outlet pipe 18. When the pressure in chamber 11 rises to a predetermined value, say 85 pounds per square inch, valve 14'will open and allow oil to pass into an outlet pipe 18. When the oil in such chamber reaches a somewhat higher pressure, say 100 pounds per square inch, valve 14 will be moved to the left far enough to uncover a port 88 and allow oil from chamber 11 to flow through this port into a chamber 8| which is connected to the suction side of pump 2. The pressure at which valve 14 opens may be varied by turning a screw 15'. An example of a pump having a pressure regulating valve such.

as described will be found in Wahlmark Patent No. 2,232,983, dated February 25, 1941, to which reference ismade for a complete disclosure of the pump and valve construction if such is necessary or desired.-

The outlet pipe 18 conducts the oil to a firing rate selector valve, mountedin a casing 83, and such-valve directs the oil to one or the other of the two oil conduits 42 and 43. The casing 88 is of magnetic material and has outlets 84 and 88, at opposite ends thereof, both leading from a central space within a sleeve 86 of non-magnetic material. The pipe 18 delivers oil into this space. Within the sleeve 86 is a slidable valve 81 oi magnetic material and a spring 88 which tends to hold valve 81 in position to close the outlet 85 and open the outlet 84. Surrounding the sleeve 86 is a solenoid 89 which, when energized, will move valve 81 against its spring into position to open the outlet 85 and close the outlet 84. This valve has been shown only diagrammatically. It is a standard three-way solenoid valve obtainable in the open market and the details of its construction are unnecessary to an understanding of this invention. The outlet 84 is connected to the oil conduit 62 which supplies the high rate nozzle 38. The outlet 85 is connected by a pipe 98 which connects, as will later appear, with the other oil conduit 43 which supplies the low rate nozzle 38..

Thus, when the solenoid 89 is de-energized, the pump 2 will supply oil to the high rate nozzle 38 and, when the solenoid is energized, the pump will supply oil to the low rate nozzle 39.

When the hot water heater isto be fired at a low rate, such as one-half gallon per hour and such as to make desirable the use of the perforated screen combustion chamber, above referred to, it will be necessary to have the oil supplied to nozzle 39 at a rate substantially less than that at which it is supplied to nozzle 38. In such case, a secondpressure regulating valve in a casing Si is provided. Within this casing, is a cylinder in which a piston 92 is slidably mounted. The niston carries a valve 93 which controls the outlet to oil conduit 43. A spring 94, acting between the piston and a seat on a screw 95, threaded into casing 9i, tends to hold the valve in closed position. When valve 81 opens outlet 85, oil at high pressure from pump 2 enters the cylinder through pipe 98 onthe side of piston 92 opposite from spring 94 and moves the piston against its spring to open valve 93. The space on the other side of the piston is connected by a pipe 96 to the suction side of pump 2, as to the suction pipe 91. Shortly after valve 93 opens, the piston 92 will move far enough to connect the space on the valve side of the piston to a groove 98 inthe cylinder wall, which groove leads to the space on the other side of the piston, whereby oil may by-pass through pipe 96 to the suction side of the pump and reduce the pressure of the oil supplied to nozzle 39. The movement of piston 92 will continue until the pressure of the oil acting on piston 92 is balanced by the pressure of spring 94, whereupon the oil red to nozzle 39 will be at the predetermined. pressure. Such pressure is. of course, variable by adjusting screw 95. This pressure regulating valve is in this instance a reducing valve. The piston 92 is provided with an opening 99 therethrough of small cross section, afiording a constant but restricted by-pass. 99 enables venting of the cylinder 3|, described before, and the cylinder of another hydraulic motor, to be later described, after valve 81'has closed the outlet to cut oil flow of oil to casing This by-pass moved back by their respective springs and to assist in such movement of the pistons.

The nozzles 38 and 39, in some cases, may have difierent rates and still operate at the same pressure, the rate being determined by the size of the nozzle orifice. Under these conditions, the second pressure-regulating valve will not be necessary. The pipe 90 would be connected at all times to pipe 43 without any valve, such as 93. Also, the pipe 90 would remain connected to pipe I20 and s the constant but restricted passage 99 would be retained to vent the cylinders of the two hydraulic motors, or other means could be provided for the purpose.

The rate at which air is supplied by fan I to the conduit 20 has to be difierent from that at which air is supplied to conduit 2| to provide for eflicient combustion, when the nozzles 38 and 39 have difierent firing rates. The rate of air supply is controlled b an air shutter I (Fig. 7), which is here shown as associated with the inlet opening I0 of the fan casing 9 although it might equally well be associated with the outlet of the fan. As shown, this shutter is of annular form, encircling the driven element 6 of the clutch and being movable axially toward and away from the inlet opening I0 to vary the rate of air flow into the fan casing 9. This shutter has fixed thereto a nut IOI into which is screwed a threaded rod I02. This rod has near its ends plain cylindrical portions, which are mounted in bearings I03 and I06, respectively formed in one side wall of fan casing 9 and in the cross bar I5. The rod is rotatable and axially movable in these bearings. Fixed to rod I02, intermediate its ends, is a clutch collar I by means of which the rod and the shutter may he moved axially from one predetermined position, such as that shown, in which the shutter is set for the higher rate of air flow necessary for conduit 20, to another predetermined position, in which the shutter is set for the lower rate of air flow for conduit 2|. The axial movement of rod I02 is limited by suitable stops, which determine the aforesaid predetermined positions. The high rate position is determined by the inner end of a screw I06, which is threaded into the end wall of a sheet metal casing I01 and which is adapted to be engaged by clutch collar I05. This casing is fixed at one end to the cross bar I5 and at the other end to fan casing 9. It encloses the shutter I00, clutch elements 6 and I, and the driving connections, except for air inlet openings I08 of ample aggregate area. The high rate position of the shutter I00 may be adjusted with precision by turning screw I06. On rod I02 is a shoulder I09, which when the rod I02 is bodily moved to the right, engages with the end face of bearing I03 to determine the low rate position of the shutter. This low rate position may be adjusted with precision by rotating screw I02 and causing the shutter to move toward or away from opening I0 to the desired degree.

For automatically moving the shutter between its two predetermined positions, a hydraulic mo tor is provided. This motor includes a cylinder IIO formed by a bore in a block III, secured by screws H2 (Fig. 3) to the wall of the passage I6 in casting l2, and a piston H3 and piston rod H4. This block III also serves to support the firing rate selector valve, its casing 83 being mounted in a hole in the block, as shown in Fig. 1. The outer end of cylinder IIO (Fig. '7) is closed by an annular plug I I5 threaded into the cylinder. A spring I I6, encircling the piston rod H4, acts between the plug H5 and piston H3 with a tendency to hold the piston in its extreme M0 to move piston II3 outwardly against spring H6 thus swinging lever III clockwise, as viewed in Fig. 7, to move clutch collar I05 and the attached rod I02 to carry the shutter I00 into its other and low rate position. Thus, whenever oil is admitted by the firing rate selector valve 81, on energization of solenoid 89, to the low rate nozzle 39, oil is also admitted to the hydraulic motor which shifts the air shutter I00 into position for operation at the low firing rate.

The other hydraulic motor 3! for operatingthe air valve 26 is also connected to receive oil at the same time as the low rate nozzle 39. This is effected by a pipe I20 (Fig. 8) which connects the cylinder of such motor to the cylinder in the valve casing 9I on the same side of piston 92 as that to which pipe is connected.

The motor 3, which drives the one air and oil supply unit for the two burners, is adapted to be started and stopped under the control of a room thermostat switch, which closes on a demand for heat from the hot air furnace and opens when such demand is satisfied, or under the control of an aquastat switch, which closes on a demand for heat from the hot water heater and opens when such demand is satisfied. The solenoid 89, which controls the oil valve 81, and indirectly the air shutter I00 and air valve 26, is arranged to be energized only when the aquastat switch is closed to start the motor. Then, the oil valve 81 is positioned to direct oil to nozzle 39; the air valve 26 is positioned to direct air to air conduit 2|; and the shutter I00 is positioned for the low rate of air flow. When the room thermostat switch closes to start the motor, the solenoid 89 is not energized and the oil valve 81 is positioned to direct oil to the high rate nozzle 38; the air valve 26 is positioned to direct air to air conduit 20 and the shutter I00 is positioned to provide the high rate of air flow.

An electrical control system for efiecting the described results is shown schematically in Fig. 9. The motor 3 is controlled by a switch I2I in a circuit com-prising the volt supply wires I22 and I23 and a wire I24. One ignition transformer, the secondary I25 of which is connected by the wires 61 to the ignition electrodes 40, has its primary I26 connected by wires I 21 and I28 to the wires I23 and I 24 and thus in parallel with motor 3. The other ignition transformer, the secondary I29 of which is connected to the electrodes M by wires I30, has its primary I 3| connected by wires I32 and I33 to wires I21 and I28, respectively, and thus in parallel with the other primary I26 and motor 3. Thus, on closure of switch I 2|, the motor 3 will be started and the primaries I26 and HI of both ignition transformers will be energized. The solenoid 89 is also connected in parallel with the motor '3 in a circuit which includes the motor switch I 2| and a second control switch I34. This circuit may be traced as follows, from supply wire I22, closed switch I2l, wire I24 to a wire I35, wire I35, closed switch I34, wire I36, solenoid 89, wire v 9 I31 to wire I21, to the left along wire I21 to supply wire I23, and wire I23.

The switch I2I is actuated by a relay, the coil of which is marked I38. This coil can be connected to one or the other of two low voltage energizing circuits, both supplied from the secondary I39 of a transformer, the primary I40 of which is connected by wires HI and I42 to the supply wires I22 and I23, respectively. One of these energizing circuits is controlled by an aquastat switch I43, adapted to be actuated by a thermostatic element I44, responsive to the temperature of the water in the hot water heater, closing when the temperature of such water falls below a predetermined value and opening when the temperature of such water rises above a predetermined value. This circuit, controlled by aquastat switch I43, may be traced as follows, from the right hand terminal of secondary I39 by wires I45, I46 and I41 to one terminal of switch I43 and from the other terminal of the latter by a wire I48 to a contact I49, 9. switch I 50, which presently engages contact I49, wire II, coil I38 and wires I52 and I53 to the left hand terminal of secondary I39. Thus, when the aquastat switch closes, coil I38 will be energized to close switch I2I and thus start the motor 3, and energize both ignition transformers and the solenoid 89. When the hot water heating burner has operated long enough to satisfy the demand, switch I43 will open and break the circuit to relay coil I38 causing switch I2I to open and stop the motor 3 and de-encrgize the two ignition transformers and the solenoid 89.

The other energizing circuit for relay coil I38 includes the described switch I50, 9. second contact I54 for the latter and a wire I55 connecting contact I54 to wire I45. This circuit may be traced as follows, from the right hand terminal of secondary I39, by wires I45 and I55, contact I54, switch I50, which is assumed to be engaged with contact I54, wire I5I, relay coil I38 and wires I52 and I53 to the left hand terminal of secondary I39. This switch I50 is actuated by a relay, the coil of which is marked I56. This coil is adapted to be energized by a circuit which is controlled by a room thermostat switch I51, which is responsive to the temperature of the rooms to be heated by the warm air furnace heated by the flame from nozzle 38, closing and opening accordingly as the temperature in such rooms is respectively below or above a predetermined temperature. When the room thermostat switch I51 closes, a circuit is closed to relay coil I56 as follows, from the right hand terminal of secondary I39, by wires I45, I46 and I58,

switch I51, wire I59, relay coil I56 and wire I53 safety devices.

back into their illustrated positions to respectively provide for high rateair flow and the connection of the outlet of fan I to the air conduit 20 leading to the combustion chamber of the warm air furnace.

It will be clear that the room thermostat switch I51 will take precedence over the aquastat switch I43 because of the switch I which opens the aquastat-controlled energizing circuit to the relay coil I38, whenever the room thermostat controlled energizing circuit for relay coil I38 is 'closed. Thus, ifthe aquastat switch is closed so that the nozzle 39 is firing the hotwater heater and a demand occurs for heat from the warm air furnace, the room thermostat switch will take the control of relay I38 away from the aquastat switch and also cause de-e'nergization of solenoid 99 to shift the air and oil supply to the warm air furnace and increase the rate of air supply proportionately to the rate at which oil is supplied to nozzle 38. Also, if the nozzle 38 is firing the warm air furnace, the aquastat switch cannot cause operation of nozzle 39 to fire the hot water heater.

It will be understood that the control system described may be used with all the customary No attempt has been made to complicate the present disclosure by the illustration and description of any of these devices. Such devices are old and 'well known in the art and an understanding of them is not necessary to an understanding of the invention.

The invention .is also independent of the control system used and may in fact be used without one.

' It will be obvious that the valve 81 could be actuated by manual control and, when so actuated, the various functions described will be accomplished in the same way. The automatic control has been described as being desirable but it is not indispensable to the invention..

The invention provides for the supply of air and *oil from one supply source to either of two burners but not to both burners at the same time. The alternate operation of the burners enables the oil and air to be supplied to each. under exactly the right conditions to effect the desired high efficiency of oil burning at each heating appliance. The valve 14 can be accurately regulated by the screw 15' to secure just the right pressure of the oil fed to the high rate nozzle 38 to deliver from the latter atomized oil at the desired rate to properly fire the warm air furnace. Then, when the valve 81 is moved by to the left hand terminal of secondary I39.

Thus, switch I50 will be moved to engage contact I54 and close the second described energizing circuit to the relay coil I38. At the same time, switch I50 will be disengaged from contact I49to break the first described and aquastatcontrolled energizing circuit to the relay coil I38. The relay coil I56 also controls the control switch I34 for solenoid 89, opening and closing such switch accordingly as the relay coil I56 is re-,

energization of solenoid 89, the oil pressure is reduced by valve 93 to the proper, and usually much lower, pressure necessary for the nozzle 39 v to deliver atomized oil at the desired rate to propvalve 14, by means of screw 95. Each oil pres-A sure may be determined with close accuracy and an automatic shift from one pressure to another will be effected coincidentally with the shifting of the oil from one burner to another by the operation of valve 81. And the air supply may also beregulated with accuracy and precision, the single shutter I00 serving to control the air supply for both burners. This shutter may be set with accuracy in one predetermined position, in which the rate of air flow is correct for the rate of oil emitted from nozzle 38 to fire the warm air furnace. Such position is that illustrated, where the collar I05, which moves with the shutter, abuts the stop I06. The latter is a screw which 11 aifords the means for a precision adjustment of said predetermined position. The shutter I may also be set with accuracy in another predetermined position, in which the rate of air flow is correct for the rate of oil emitted from nozzle 39 to fire the hot water heater. This second predetermined position is determined by the stop, which in this case consists of the end face of bearing I03. The shutter-supporting threaded rod I02, being rotatable in the shutter nut IOI, provides the means for a precision adjustment of the second predetermined position by moving the abutment I09 on the threaded rod relatively to the fixed stop I03. Then, the hydraulic motor IIOI I3 provides for automatically shifting the shutter from one of said predetermined positions to the other. This motor and the hydraulic motor, which shifts the air valve 26, are interlocked with the oil valve 81 because when oil under pressure from the pump is directed by this oil valve to the low rate nozzle 39, some of this oil is simultaneously fed to both motors to shift the air valve 26 to connect air conduit 2| to the outlet of fan I and to shift shutter I00 into its low rate position. When the oil valve is turned to cut oif oil supply to nozzle 39, both motors are simultaneously connected to the suction side of the pump and their springs come into action, in one case to shift air valve 26 to connect conduit 20 to the fan outlet and in the other case to shift the shutter to its high rate position.

The invention thus provides a dual oil burner of the oil pressure atomizing type for use in alternately firing a warm air furnace for room heating and a heater for the household hot water system, characterized in that the one poweroperated oil and air supply unit may supply the oil and air at differentrates, each closely regulable independently of the other, to the different burners so that each heating appliance may be fired with equal and high efliciency.

We claim:

1. A dual oil burner, comprising, a fan casing having inlet and outlet openings, two air conduits connected to the casing to receive air from the outlet opening, an air valve movable from one position to another to connect one or the other ofsaid conduits to receive air from the fan casing and operable when connecting either one of the conduits to disconnect the other, a fan in said casing, a motor for driving the fan, an adjustable shutter to control one of said openings in the fan casing and determine the rate at which air is supplied by said fan, said shutter being mounted for movement toward and away from said one opening, stationarily-supported stops for limiting the movement of the shutter in JbO'i/h directions to one or the other of two predetermined positions, an oil pump driven by said motor, two oil conduits-and an oil valve for connecting one or the other of them at one end to the pump, said oil conduits extending one into one air conduit and the other into the other air conduit, oil-atomizing nozzles one on the other end of each oil conduit, and means for moving said air valve and shutter, operatively interlocked with said oil valve so that the fan will be connected to supply air to oneair conduit when the pump is connected to supply oil to the oil conduit and nozzle in such air conduit and the shutter will be moved into that predetermined position which will determine the proper rate of air flow for such air conduit.

2. A dual oil burner, comprising, a fan casing having inlet and outlet openings, two air con- 12 duits connected to the casing to receive air from the outlet opening, an air valve movable from one position to another to connect one or the other of said conduits to receive air from the fan casing and operable when connecting either one of the conduits to disconnect the other, a fan in said casing, a motor for driving the fan, an adjustable shutter to control one of said openings in the fan casing and determine the rate at which air is supplied by said fan, said shutter being mounted for movement toward and away from said one opening, stationarily-supported stops for limiting the movement of the shutter in both directions to one or the other of two predetermined positions, precision adjusting means for moving the shutter and stops the one relatively to the other to accurately determine each of said predetermined positions, an oil pump driven by said motor, two oil conduits, and an oil valve for connecting one or the other of them at one end to the pump, said oil conduits extending one into one air conduit and the other into the other air conduit, oil-atomizing nozzles one on the other end of each oil conduit, and means for moving said air valve and shutter, operatively interlocked with said oil valve so that the fan will be connected to supplyair to one air conduit when the pump is connected to supply oil to the oil conduit and nozzle in such air conduit and the shutter will be moved into that predetermined position which will determine the proper rate of air flow for such air conduit.

3. A dual oil burner, comprising, a fan casing having inlet and outlet openings, two air conduits connected to the casing to receive air from the outlet opening, an air valve movable from one position to another to connect one or the other of said conduits to receive air from the fan casing and operable when connecting either one of the conduits to disconnect the other, a fan in said casing, a motor for driving the fan, an adjustable shutter to control one of said openings in the fan casing and determine the rate at which air is supplied by said fan, said shutter being mounted for movement toward and away from said one opening, stationarily-supported stops for limiting the movement of the shutter in both directions to one or the other of two predetermined positions, an oil pump driven by said motor, two oil conduits, and an oil valve for connecting one or the other of them at one end to the pump, said oil conduits extending one into one air conduit and the other into the other air conduit, oil-atomizing nozzles one on the other end of each oil conduit, hydraulic motor means operatively connected to the air valve and shutter for moving them from one position to the other, and an oil conduit from said means to said pump and controlled by said oil valve to admit oil from said pump to the motor means to move the air valve to connect one air conduit to the fan when the oil valve connects the oil conduit in such air conduit to the pump and to move the shutter into that predetermined position which will determine the proper rate of air flow for such air conduit.

4. A dual oil burner, comprising, a motor driven pump and fan for respectively supplying oil and air for combustion, said fan having a casing with inlet and outlet openings, first and second air conduits connected to the casing to receive air from the outlet opening, an air valve for connecting one or the other of said air conduits to receive air from said fan, first and second oil conduits extending at one end into the first and second air conduits respectively, first and secof the first and second oil conduits respectively and having diflerent firing rates, a valve for connecting one or the other of said 011 conduits to said pump, an adjustable shutter to control one of said openings in the fan casing, and movable between first and second predetermined positions to respectively determine the proper rate of air flow for the first and second air conduits, stationarily mounted stops for limiting the movement of the shutter in both directions to one or the other of said positions, precision adjustin means for relatively moving the stops and shutter to accurately determine said predetermined positions, hydraulic motor means operatively connected to said air valve and shutter and operable when supplied with liquid under pressure to move them in one direction, said motor means including yieldable means for moving said air valve and shutter in the other direction and holding the air valve positioned to connect the fan to the first air conduit and the shutter in said first position, yieldable means for holding the oil valve positioned to connect the first oil conduit to said pump, and a conduit connection between said motor means and pump controlled by the oil valve and closed when the latter is positioned to connect the first oil conduit to-the pump, said valve when positioned to connect the second oil conduit to the pump also operable to connect the oil conduit of said motor means to said pump to admit oil under pressure thereto and move the air valve and shutter against said yieldable means to carry the air valve into position to connect the second air conduit to the fan and move the shutter into its second predetermined position.

5. A dual oil burner, comprising, a fan casin having inlet and outlet openings, two air conduits connected to the casing to receive air from the outlet opening, an air valve movable from one position to another to connect one or the .other of said conduits to receive air from the fan casing and operable when connecting either one of the conduits to disconnect the other, a fan in said casing, a motor in driving the fan, an adiustable shutter to control one of said openings in the fan casing and determine the rate at which air is supplied by said fan, said shutter being mounted for movement toward and away from said one opening, stationarily-supported stops for limiting the movement of the shutter in both directions to one or the other of two predetermined positions, precision adjusting means for moving the shutter and stops the one relatively to the other to accurately determine each of said predetermined positions, an oil pump driven by said motor, two oil conduits, and an oil valve for connecting one or the other of them at one end to the pump, said oil conduits extending one into one air conduit and the other into the other air conduit, oilatomizing nozzles one on the other end of each oil conduit, independently-adjustable pressure-regulating valves one to determine the pressure of oil fed to one oil conduit and one for determining the pressure of'oil fed to the other oil conduit, and means for moving said air valve and shutter, operatively interlocked with said oil valve so that the fan will be connected to supply air to one air conduit when the pump is connected to'supply oil to the oil conduit and nozzle in such air conduit and the shutter will be moved into that predetermined position which will determine the proper rate of air how for such air conduit.

JOSEPH A. LOGAN. PHILIP H. BILLS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,637,820 Hawkins Aug. 2, 1927 1,985,934 Logan Jan. 1, 1935 2,039,910 Kriechbaum May 5, 1936 2,075,334 Braden Mar. 30, 1937 2,232,983 Wahlmark Feb. 25, 1941 2,315,412 Galumbeck Mar. 30, 1943 2,353,146 cheasley July 11, 1944 2,358,809 Jennings Sept. 26, 1944 2,395,487 Logan Feb. 26, 1946 2,411,048 Logan Nov. 12, 1946 

